We have had our 97 528iA for about 3 months now. With the heavy thunderstorms lately in CT I noticed twice that the next day, when I would open the sunroof, water would drip onto the rear seat. Prior to opening it there is no evidence of leaking or while riding in the rain there is no water. It usually appears the next day. Anyone else have this happen? Is there a fix, we just passed the 50K miles but have the extended warranty.